The purpose of this study was to investigate the effects of preexhausting
a synergistic secondary mover prior to performing a
compound exercise. Pre-exhaustion involves intentionally fatiguing
a large muscle group in isolation prior to performing a compound
exercise that utilizes the same muscle (e.g. performing glenohumeral
joint horizontal adduction with a machine flying exercise immediately
prior to barbell bench press in order to increase activation of pectoralis
major. Surface electromyography was utilized to analyze the effects
of pre-exhaustion of the triceps brachii on the pectoralis major while
performing the barbell bench press. Data from the pectoralis major
for 12 males were recorded during the barbell bench press; subjects
performed this exercise with and without pre-exhaustion of the
triceps brachii. A significant increase in electromyographic activity
was noted in the pectoralis major (z = -2.353, p = 0.019) following
pre-exhaustion of the triceps, indicating that pre-exhaustion of a
synergistic secondary mover may result in higher neuromuscular
activation of the primary mover in a compound exercise. Additional
research with a larger sample size will provide more conclusive
findings.

Keywords: Pre-Exhaustion; Neuromuscular Activation

Introduction

Exercise order is important to consider when designing a
resistance-training program. Repetition performance [1, 2],
strength [3, 4, 5, 6], force [7], power [7,8], and muscle volume
[3, 4] have all been shown to be effected by the sequencing of
exercises. Pre-exhaustion (PRE) is a method of exercise ordering
that has been promoted in layperson bodybuilding literature.
PRE involves intentionally fatiguing a large muscle group in
isolation prior to performing a compound exercise that utilizes
the same muscle (e.g. performing glenohumeral joint horizontal
adduction with a machine chest flying exercise immediately
prior to barbell bench press in order to increase activation of
pectoralis major (PM)) [9]. While current research [10, 11,
12, 13] on PRE has shown that this technique results in lower
activation of the targeted muscle, it also demonstrated that PRE
can result in increased neuromuscular activation of synergistic
muscles[11,12,13].

Subjects have performed the bench press with and without
PRE of PM with a dumbbell chest flying exercise (2 dumbbells
are simultaneously moved vertically from a position of shoulders
horizontally abducted at 90° to nearly 0°)[12]. Electromyographic
(EMG) data were recorded for the pectoralis major (PM), anterior
deltoid (DA), and triceps brachii (TB). No significant changes
in the tonic control of PM and DA were noted between the two
treatment groups, however, TB did have a significantly (p < .05)
higher motor unit activation when the chest was pre-exhausted
with a dumbbell chest flying exercise.

Gentil et al. [11] compared upper-body muscle activation
between PRE and the priority system, which involves performing
complex exercises first in a strength-training program prior to
performing single joint exercises. EMG data were recorded for
TB, DA, and PM. The authors found TB activity to be significantly
(p < 0.05) higher when the PRE method was used, however no
difference was noted between the PRE and the priority system
for DA and PM. Future investigation on the effects of fatiguing
a synergistic muscle group prior to performing the primary
exercise movement remains a research priority. Simao et al
[14] echoed this in a review underscoring the importance of
evaluating the effects associated with pre-exhausting muscle
groups other than PM and the quadriceps.

There is a paucity of literature assessing the effects of preexhausting
a synergistic secondary mover in isolation with
a single-joint exercise prior to performing a compound lift.
Therefore we investigated the effects of PRE of the triceps brachii
prior to performing the barbell bench press, hypothesizing that
this ordering of exercises will result in higher neuromuscular
activation of the PM.

Methods

Subjects

Males between 20 and 35 years of age (24, ± 1.5 years)
were invited to participate. On average subjects weighed 88
± 8 kg, were 183 ± 6.3 cm in height, and performed resistance
training at least three times per week during the previous twelve months, with lifting experience that spanned 9 ± 2 years. Men
were excluded from the study if they had a history of significant
upper-body injury or any health conditions that presented
with contraindications to participation in a strength-training
program. All subjects were informed of the purpose, procedures,
and risks associated with this study and were informed they
could withdraw from participation at any time. Twelve men
participated in the study.

Experimental Design

The 2-sequence, 2-period, 2-treatment balanced cross-over
design performed by Gentile et al. [11]was replicated; however
the washout period was extended from 20 to 30 minutes to 72
hours in order to ensure adequate recovery from the first testing
session. Surface electromyography (EMG) was used to detect
the neuromuscular activation of pectoralis major (PM) during
two testing sessions: T1 (pre-exhaustion of triceps brachii prior
to performing the bench press); T2 (only bench press). Group
AB performed protocol T1, rested 72 hours, and then preformed
protocol T2. Group BA performed protocol T2, rested 72 hours,
and then preformed protocol T1 (Table 1).

Electromyography

EMG measurements were taken on the subjects' dominant
side of the body. A 5 cm self-adhesive, circular, bipolar shielded,
silver-silver chloride Triode electrode (Thought Technology
Limited, Quebec, Canada) was utilized. Subjects were instructed
to shave their chest prior to arrival. Recommendations from
Florimond [15] were followed for anatomical placement of the
electrodes. The site of electrode placement was identified and
inspected by the same investigator. Tests were initiated once
less than 5 μV of resting EMG activity was observed [15].

Raw EMG signals were recorded using the Flex Comp Infinity
encoder, and Myo Scan sensor (Thought Technology Limited,
Quebec, Canada). Data were analyzed using Bio Graph Infiniti
software (Thought Technology Limited, Quebec, Canada). The
signal was recorded with a Common Mode Rejection > 130 dB,
and a fifth order Butterworth filter, with 30 dB alias rejection,
was applied. Following this, the data were pre-amplified with a
gain of 500 and band pass-filtered between 10 and 1000 Hz, with
a sample rate of 2048 samples/second.

Determination of 10 Repetition Maximum Load

Grip width for the bench press and triceps extension were
normalized by subjects' bi-acromial width. Subjects were
instructed on proper lifting technique, and an automated
metronome was played to assist subjects in following a 2-0-2
(eccentric, isometric, concentric) tempo. Subjects performed the
barbell bench press at a weight that they estimated they could
lift approximately 10 times without compromising technique or
rate. If subjects performed more or less than 10 repetitions, the
weight was adjusted by 5-pound increments. 5 minutes of rest
were taken between sets. A minimum of one and a maximum
of three attempts were performed. A 20-minute rest period
followed, and then the same protocol was repeated for the triceps
extension exercise. Subjects were asked to not make any changes
to their normal levels of physical activity, with the exception of
not exercising the chest, triceps, or anterior shoulders for 72
hours prior to their testing sessions.

Experimental Protocol

Subjects warmed up on the bench press with 10-15 repetitions
at 50% of their estimated 10-repetition maximum load. Three
maximum voluntary isometric contractions (MVIC) of the PM
were performed against a fixed resistance with shoulders

Table 1: Protocol for the two different groups.

Group

10 Rep max Test Day(Triceps Extension + Bench Press)

Maximal Voluntary Isometric contraction (each test day)

Bench Press without PRE

Bench Press with PRE

AB

1st day

Yes

2nd day

3rd day

AB

1st day

Yes

3rd day

2nd day

flexed to 90°, elbows extended to 0°, and forearms pronation.
A one second ramp up period was followed by 4 seconds of
maximal contraction. Subjects rested for 20 seconds between
repetitions, and for five minutes before beginning testing. For
protocol T1, subjects performed the bench press exercise at
their previously determined 10 repetition maximum load. For
protocol T2, subjects performed one set of a triceps extension
exercise to fatigue at the previously determined 10 repetition
maximum load, and immediately moved to the bench press to
perform repetitions to fatigue at the previously determined 10
repetition maximum load. In both protocols, testing ceased if
the participants' form was compromised or if they were unable
to maintain proper tempo. EMG data were collected for the
PM during the barbell bench press for both protocols. Subjects
were asked to not make any changes to their normal levels of
physical activity, with the exception of not exercising the chest,
triceps, or anterior shoulder for 72 hours prior to performing the
alternative protocol.

Data Analysis

Raw EMG data were analyzed using Biograph Infiniti software
(version 5.1.2).The average signal amplitude was calculated using
the root mean square method. A blinded investigator identified
peak MVIC values according to protocol established by Thought
Technology[15].The first and last repetitions were visually
identified and removed from the dataset to eliminate artifact
caused by the racking and unracking of the bar. The amplitude
was normalized to the mean of the peak EMG values obtained
during the MVIC tests for each subject.

Statistical Analysis

Normalized RMS values for exercise protocol T1 and T2 were
compared using the Wilcoxon signed rank test. Total repetitions,
mean time per counted repetition, and mean MVIC were
compared between groups AB and BA using a paired samples
t-test. All results are presented in values of mean ± SD; an alpha
level of 0.05 was used for all comparisons.

Results indicated that pre-exhaustion of TB with a triceps
extension exercise could result in higher neuromuscular
activation of PM during a bench press exercise than when no preexhaustion
is performed. The observed altered recruitment of
a primary mover after PRE of a synergistic secondary mover is
similar to the outcome of other studies [11, 12, 13], which showed
that PRE of a primary mover could result in altered recruitment
patterns of synergistic muscles. Gentil et al. [11] and Brennecke
et al. [12] pre-exhausted pectoralis major before the performance
of the bench press, and both authors observed a significant (p <
.05) change in the neuromuscular activation of TB.Akima et al.
[13]demonstrated increased activation of vastusmedialis and
rectus femoris after PRE of VL through electromyo stimulation.

A review of current research on exercise ordering in
resistance training performed by Simão et al. [14] concluded that
if an exercise is important it should be placed at the beginning
of the exercise sequence. Our findings suggest that future
research investigating the chronic effects of PRE of a synergistic
secondary mover prior to performance of a compound exercise
may reveal an alternative, and perhaps more appropriate, form
of exercise sequencing than the current recommendations.
Miranda et al. [16] investigated all possible ordering sequences
for bench press (BP), triceps extension (TE), and shoulder press
(SP) and concluded that the only significant effect on repetition
performance occurred during the SP, TE, BP sequence when
compared to the TE, BP, SP and the TE, SP, BP sequences. The
SP, TE, BP sequence resulted in significantly less repetitions

performed. Therefore, placing TE prior to BP might not affect
repetition performance during a three-exercise sequence.
In addition to conducting a long-term study on the chronic
effects of PRE of a secondary synergist, future research should
also investigate the acute affects of this exercise sequence on
additional local musculature such as the anterior deltoid, and
triceps brachii.

Previous research [11, 12] assessing the effects of preexhausting
pectoralis major with a single-joint exercise prior to
performing the barbell bench press demonstrated that the PRE
method is not effective in accomplishing the goal promoted in
layperson bodybuilding literature. We incorporated subjects of
similar age and lifting experience to these studies [11, 12] and
found that the goal of PRE can possibly be accomplished by preexhausting
the TB prior to the barbell bench press. Additional
inquiry with a larger sample will provide more conclusive
findings.